This invention relates, in general, to a method of operating chemical sensors, and more particularly, to a method of operating chemical sensors which reduces power consumption.
Chemical sensors are used to monitor dangerous and other toxic gases including carbon monoxide, methane, hydrogen, automobile exhaust, and biomedical and industrial emissions. Generally using an ac power source, chemical sensors need to have a backup power supply, such as a battery, which should last for several days to ensure reliability of the chemical sensor system Moreover, with the constantly growing need for more portable systems and remotely controlled systems, many chemical sensors need to rely entirely on battery powered operation. However, current methods of operating metal oxide based chemical sensors consume large quantities of power which drastically shorten battery life and, therefore, are not suited for portable applications or battery powered backup operations.
Previous attempts have been made to reduce power consumption by, among other methods, altering the size and composition of chemical sensors, adding heat reflectors and thermal insulators to the chemical sensors, and pulsing a single heater of a single sensor element. However, none of the prior schemes for a low power consumption system have significantly extended battery life to a practical or efficient level Alternative technologies including optically based sensors are currently battery powered but are compatible with neither low cost silicon fabrication nor integration schemes.
Existing gas monitoring schemes do not compensate for varying environmental factors. For instance, temperature and humidity fluctuations can detrimentally affect the accuracy of chemical sensors. Therefore, environmental calibration is a necessary feature for reliable and precise chemical sensors.
Furthermore, redundancy in gas detection is a desirable feature to further improve the reliability and safety of chemical sensors.
Accordingly, a need exists for a method of operating chemical sensors which is compatible with battery powered operation for backup, portable, and remotely controlled applications. The method should increase battery life up to a pragmatic level, should maintain a safe and reliable detection scheme, and should not be expensive. The method should permit environmental calibration and should also incorporate gas sensing redundancy.